1. Field of the Invention
This invention relates to an openable motor vehicle roof with a movable roof element for selectively closing and at least partially clearing a roof opening, a body-mounted frame component which extends over at least one edge area of the roof opening, a seal element which is located in the area of the frame component, and against which the roof element rests when the roof opening is being closed, an electric motor drive for moving the roof element, and a monitoring means which is coupled to the drive and which evaluates the drive parameters derived from the drive and turns off and optionally reverses the drive when it is recognized using the evaluation of the drive parameters that there is a interfering body between the roof element and the edge area of the roof opening.
2. Description of Related Art
In motor vehicles, for closing elements, especially electrically actuated windows, automatically closing doors or electrically activated roofs, which are actuated by an outside force, two types of crush protection devices are used, as is explained, for example, in EP 0 870 892.
In one type of crush protection, pressure-actuated sensor elements are used which are provided on a closing edge and which, when exposed to pressure, turn off or reverse the drive of the closing element. In another type of crush protection, information about possible crushing is taken from the power data of the drive unit for the closing element. In particular, the motor current tapped on the drive or the torque delivered by the drive motor can be monitored, and both rise in the case of crushing. Furthermore, via evaluation of the motor revolutions and/or rpm of the drive the position and/or speed information can be evaluated with respect to the adjustable roof element in order to implement obstacle detection. If predetermined boundary values of the respectively interrogated parameters are not reached or are exceeded, the drive unit is turned off, and optionally, the direction of motion is reversed.
Especially for motor vehicle roofs in which the movable roof element rests against a seal element at the end of its closing motion, crush protection of the latter type often cannot be reliably implemented since the change of the drive parameters caused by the crushed interfering body is superimposed on the change of the drive parameters which is caused by the deformation of the seal element. Especially for motor vehicle roofs in which the roof element for closing the roof opening pivots from overhead against the body-mounted frame, as is the case, for example, for externally guided sliding roofs and also for convertible roofs, the problem also arises that the roof element strikes the interfering body at a relatively acute angle so that the interfering body does not abruptly block the motion of the roof element, but rather leads to gradual jamming of the roof element; this is not necessarily interpreted as crushing of the interfering body by the monitoring means which is coupled to the drive.